Recently, as external preparations such as cosmetics, external preparations formed by soft capsules (soft capsule bodies having a small spherical shape) come onto the market and draw attention. The reason for this is that the soft capsule has features that an effective ingredient can be stably contained therein, soft feeling is popular, and a high grade is achieved, for example.
In addition, among the external preparations formed by soft capsules, for example, the following patent applications have been made as an example which is contrived such that an external preparation is easily broken by rubbing at the time of applying the external preparation to skin and residues or a film thereof does not remain.
(Patent Document 1)
In JP 11-29433 A (Patent Document 1, JP 3151169 B1) relevant to the patent application of the present applicant, there is described “a capsule-containing cosmetic in which “a barium alginate-based capsule A,” which is formed by alginate to be a spherical body and in which at least a part of alginate present at a surface side or the surface side and an inner side of the spherical body is present in the form of a polyvalent metal salt containing a barium salt, is present in “an external solution B composed of an aqueous solution of a pH-adjusted carboxy vinyl polymer.” The reason why the pH-adjusted carboxy vinyl polymer is caused to be present in the external solution B is that the barium alginate-based capsule A is caught in a three-dimensional network of the carboxy vinyl polymer in the external solution B so as to make the capsule A not to be precipitated or not to be floated (Paragraph [0058]).
In this Patent Document 1, there is described a method for producing a capsule-containing cosmetic, in which the aqueous solution of the carboxy vinyl polymer is mixed with the barium alginate-based capsule A and a pH adjuster at the same time or in an arbitrary order, and the barium alginate-based capsule A is caused to be present in the external solution B composed of the aqueous solution of the pH-adjusted carboxy vinyl polymer. Here, as the pH adjuster used when pH of the aqueous solution of the carboxy vinyl polymer is adjusted, there is a description that “Sodium hydroxide is particularly preferable, but in addition to this, sodium carbonate, sodium bicarbonate, triethanolamine, diethanolamine, monoethanolamine, L-arginine, DL-alanine, sodium citrate, sodium hydrogen citrate, sodium malate, sodium tartrate, sodium malonate, sodium lactate, sodium oxalate, sodium polyacrylate, or the like can also be used.” (Paragraph [0032]). Incidentally, in Example 1, Comparative Example 1, and Example 2 of this Patent Document 1, pH of the aqueous solution of 1% by weight of carboxy vinyl polymer is 3, but pH adjustment is performed by addition of an aqueous solution of potassium hydroxide such that pH of the external solution B is adjusted to 6.0 or 6.5 (Paragraphs [0044], [0049], and [0053]). That is, since pH of the aqueous solution of 1% by weight of carboxy vinyl polymer is as low as 3, pH adjustment is performed by addition of an alkaline substance.
(Patent Document 2)
In JP 5-92909 A (Patent Document 2, JP 2798224 B1) relevant to the patent application of the present applicant, there is described a cosmetic in which a caviar-shaped capsule A in which only a surface portion is formed by a film and which is easily broken by rubbing is caused to be present in a liquid agent B. The capsule A is obtained by adding a dropping liquid composed of sodium alginate and another water-soluble aqueous solution dropwise to a receiving liquid of a water-soluble calcium salt or the like. Attention is paid so that the caviar-shaped capsule A which is easily broken by rubbing is obtained by setting a concentration of sodium alginate of the dropping liquid or a concentration of the water-soluble calcium salt of the receiving liquid at the time of obtaining the capsule A to an appropriate concentration. Then, the capsule A obtained in this way is caused to be floated or precipitated in the liquid agent B such as water, saline solution, emulsion, or skin toner (Paragraphs [0028], [0029], and [0038]).
(Patent Document 3)
In JP 5-228218 A (Patent Document 3) relevant to the patent application of the present applicant, there is also described a care product including: a capsule container 1 accommodating a pearl-shaped capsule A, which is obtained in the same manner as in the above Patent Document 2 and is easily broken by rubbing, in a container provided with an extraction mechanism in a state where the capsule A is swollen by a liquid agent B; and a compact massaging tool 2 by which stimulation is given to the vicinity of an eye.
(Patent Document 4)
In JP 8-175932 A (Patent Document 4) relevant to the patent application of the present applicant, there is described a foundation cosmetic obtained by accommodating, in a container, a mixture of a foundation capsule which is composed of a composition having a powder material for foundation as an effective ingredient and is easily broken by rubbing and in which only a surface portion is formed by a film (in Paragraph [0040], sodium alginate is used), a small caviar-shaped moisturizer capsule which is composed of a composition having a moisturizer as an effective ingredient and is easily broken by rubbing and in which only a surface portion is formed by a film (in Paragraph [0043], sodium alginate is used), and a gel-type viscous liquid (in Paragraph [0046], carboxy vinyl polymer, DL-alanine, and sodium citrate are used).
(Patent Document 5)
In JP 2-117610 A (Patent Document 5), there is described an emulsion encapsulated capsule-containing cosmetic, the cosmetic containing a capsule encapsulating O/W type emulsion, in which a capsule film is composed of 0.1 to 1.0% by weight of calcium alginate with respect to the total weight of the capsule. The capsule film is formed by reacting water-soluble alginate with a water-soluble calcium salt to purify water-insoluble calcium alginate. In Example 1 of this patent document, there is a description that the capsule film does not remain after using, and in Example 2 of this patent document, in addition to the capsule, a formulation of a cosmetic liquid in which a citric acid and sodium citrate are blended is described.
(Patent Document 6)
In claim 1 of JP 2011-74002 A (Patent Document 6), there is described “A capsule comprising a gel metal salt of Aphanothece sacrum polysaccharide as an outer skin thereof.” In claim 2 of this patent document, there is described “The capsule according to claim 1, containing an aqueous solution of a water-soluble component,” and based on the description in claim 2, regarding the water-soluble component, there is description in Paragraph [0011] on “amino acids such as arginine, alanine, . . . and salts and derivatives thereof.”
Patent Document 1: JP 11-29433 A
Patent Document 2: JP 5-92909 A
Patent Document 3: JP 5-228218 A
Patent Document 4: JP 8-175932 A
Patent Document 5: JP 2-117610 A
Patent Document 6: JP 2011-74002 A